Heat oven to 400 degrees F. Place oven rack in upper third of oven.
Heat oil in large nonstick skillet. Add onion; saute 4 minutes. Add garlic; saute 2 minutes. Add mushrooms; saute 3 minutes. Stir in spinach, salt and pepper; cook 5 minutes, until spinach is tender. Stir in 2 tablespoons Alfredo sauce.
Place largest crepe on 9-inch pie plate. Brush with 1 tablespoon Alfredo sauce. Spread with 2 tablespoons spinach filling. Sprinkle with 1-1/2 tablespoons mozzarella and 1/2 teaspoon Parmesan. Repeat until all crepes and filling are used; leave top crepe plain. Pour rest of Alfredo sauce over; top with Parmesan.
Bake in upper third of 400 degree F oven 15 minutes. Let stand 15 minutes before cutting into wedges. Makes 4 servings.
Beat eggs and milk in bowl at low speed to blend. Beat in flour and salt. Stir in melted butter. Refrigerate at least 30 minutes. Batter should be like heavy cream; if too thick, thin with milk. Heat 8-inch crepe pan or skillet; coat with cooking spray. Pour in 2 tablespoons batter, swirling pan. Brown bottom side, 2 to 3 minutes. Repeat with rest of batter, stacking crepes between waxes paper